#Elements in e_blockqueue and e_boardblock are in the form (rot<<3) + idx


mkarray "e_blockqueue" store  #(rot<<3) + idx

@defun "e_init" {
	-1 ntiles_x ntiles_y * replicate
	ntiles_x ntiles_y * mkarrayp
	"e_boardblock" gstore  #(rot<<3) + idx

	0 ntiles_x ntiles_y * replicate
	ntiles_x ntiles_y * mkarrayp
	"e_boardfilled" gstore  #booleans

	e_pushnewblock
	e_newcblock  #initialises cblock vars
}

@defun "e_test" {
	0 "i" store
	i b_nblocks < while
		0 "j" store
		j 4 < while
			io_clearscreen
			io_windowbox
			0 0 i j b_drawblock
			1000000 sleep
			j 1 + "j" store
		j 4 < end
		i 1 + "i" store
	i b_nblocks < end
	io_pos_after io_goto
}

@defun "e_nextblock" {
	"e_blockqueue" swapoutvar
	arrlen 1 < if
		"ERROR: blockqueue empty while requesting nextblock" print
		error
	end
	0 arridx
	swap
	arrpopf "e_blockqueue" gstore
	e_pushnewblock
}

@defun "e_peekblock" {
	"e_blockqueue" swapoutvar
	arrlen 1 < if
		-1
	else
		0 arridx
	end
	swap
	"e_blockqueue" gstore
}

@defun "e_pushnewblock" {
	"e_blockqueue" swapoutvar
	0 7 randr arrpush
	"e_blockqueue" gstore
}

@defun "e_newcblock" {
	e_nextblock "e_cblock" gstore
	ntiles_x 2 - 2 / "e_cblockpos" gstore
}

@defun "e_fullrender" {
	io_clearscreen
	io_windowbox

	io_printheader

	"e_boardblock" swapoutvar
	arrlen "sz" store
	0 "i" store
	i sz < while
		i arridx
		dup -1 = ! if
			i ntiles_x % swap
			i ntiles_x / swap
			dup 8 % swap 8 /
			b_drawblock
		else
			pop
		end
		i 1 + "i" store
	i sz < end
	"e_boardblock" gstore

	io_pos_windowend pop 4 + 2 io_pos_windowstart add2 io_goto
	"Next block:" print
	ntiles_x 3 + 1
	e_peekblock dup 8 % swap 8 /
	b_drawblock

	e_cblockpos dup ntiles_x % swap ntiles_x /
	e_cblock dup 8 % swap 8 /
	dup4
	b_drawblock
	sleep_time sleep
	b_undrawblock
}

@defun "e_validcbp" { #args: cblock cblockpos (compares purely to e_boardfilled)
	dup ntiles_x % swap ntiles_x / "cbposy" store "cbposx" store
	dup 8 % swap 8 / b_getblock "bits" store
	1 "retval" store
	0 "y" store
	bits while
		0 "x" store
		x 4 < bits !! & while
			bits 1 & if
				cbposx x + 1 <
				cbposx x + ntiles_x 1 - > |
				cbposy y + ntiles_y 1 - > | if
					0 "retval" store
					0 "bits" store  #make the loops break
				else
					"e_boardfilled" swapoutvar
					ntiles_x cbposy y + * cbposx x + +
					arridx
					swap "e_boardfilled" gstore
					if
						0 "retval" store
						0 "bits" store  #make the loops break
					end
				end
			end
			bits 2 / "bits" store
			x 1 + "x" store
		x 4 < bits !! & end
		y 1 + "y" store
	bits end
	retval
}

@defun "e_applyblock" { #args: block blockpos
	dup "blockpos" store
	dup ntiles_x % swap ntiles_x / "blockposy" store "blockposx" store
	dup "block" store
	dup 8 % swap 8 / b_getblock "bits" store

	"e_boardblock" swapoutvar
	block blockpos arrset
	"e_boardblock" gstore

	"e_boardfilled" swapoutvar
	0 "y" store
	y 4 < bits !! & while
		0 "x" store
		x 4 < while
			bits 1 & if
				1 blockposy y + ntiles_x * blockposx x + + arrset
			end
			bits 2 / "bits" store
			x 1 + "x" store
		x 4 < end
		y 1 + "y" store
	y 4 < bits !! & end
	"e_boardfilled" gstore
}

@defun "e_runloop" {
	1 while
		e_fullrender
		e_cblockpos ntiles_x + #new cblockpos
		dup e_cblock swap e_validcbp if
			"e_cblockpos" gstore
		else
			pop
			e_cblock e_cblockpos e_applyblock
			e_newcblock
		end
	1 end
}